U.S. patent number 7,652,812 [Application Number 11/547,867] was granted by the patent office on 2010-01-26 for method of powering an electrically-controlled device with variable optical and/or energy properties.
This patent grant is currently assigned to Saint-Gobain Glass France. Invention is credited to Fabien Beteille, Xavier Fanton, Carinne Fleury, Erwan Mahe, Emmanuel Valentin.
United States Patent |
7,652,812 |
Mahe , et al. |
January 26, 2010 |
Method of powering an electrically-controlled device with variable
optical and/or energy properties
Abstract
A method of supplying an electrically controllable system having
variable optical/energy properties in transmission or in
reflection, including at least one carrier substrate with a
multilayer that allows migration of active species, including at
least two active layers separated by an electrolyte, the multilayer
being placed between two electrodes connected respectively to upper
and lower current leads respectively. In addition to a constant
first energy potential, a time-varying second energy potential is
applied between the current leads, the first and second energy
potentials being designed to ensure switching between two states
having different optical/energy properties in transmission or
reflection.
Inventors: |
Mahe; Erwan (Guerande,
FR), Beteille; Fabien (Revel, FR), Fleury;
Carinne (Saint Prim, FR), Valentin; Emmanuel (Le
Plessis Trevise, FR), Fanton; Xavier (Aulnay sous
Bois, FR) |
Assignee: |
Saint-Gobain Glass France
(Courbevoie, FR)
|
Family
ID: |
34944413 |
Appl.
No.: |
11/547,867 |
Filed: |
April 7, 2005 |
PCT
Filed: |
April 07, 2005 |
PCT No.: |
PCT/FR2005/050218 |
371(c)(1),(2),(4) Date: |
January 19, 2007 |
PCT
Pub. No.: |
WO2005/103807 |
PCT
Pub. Date: |
November 03, 2005 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20080018979 A1 |
Jan 24, 2008 |
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Foreign Application Priority Data
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Apr 9, 2004 [FR] |
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04 03800 |
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Current U.S.
Class: |
359/265; 396/457;
345/105 |
Current CPC
Class: |
G02F
1/163 (20130101); B32B 17/10174 (20130101); B32B
17/10036 (20130101) |
Current International
Class: |
G02F
1/15 (20060101) |
Field of
Search: |
;359/265 ;345/105
;396/457 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0 638 835 |
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Feb 1995 |
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EP |
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58 125018 |
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Jul 1983 |
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JP |
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61 254935 |
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Nov 1986 |
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JP |
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98 16870 |
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Apr 1998 |
|
WO |
|
Other References
US. Appl. No. 11/817,685, filed Sep. 4, 2007, Fanton, et al. cited
by other .
U.S. Appl. No. 11/547,867, filed Jan. 19, 2007, Mahe, et al. cited
by other.
|
Primary Examiner: Martinez; Joseph
Attorney, Agent or Firm: Oblon, Spivak, McClelland, Maier
& Neustadt, L.L.P.
Claims
The invention claimed is:
1. A method of supplying an electrically controllable system having
variable optical/energy properties in transmission or in
reflection, including at least one carrier substrate with a
multilayer that allows migration of active species, or an
electrochromic multilayer including at least two active layers,
which are separated by an electrolyte, the multilayer being placed
between two electrodes connected respectively to upper and lower
current leads respectively, the method comprising: applying, a
constant first energy potential and a time-varying second energy
potential between the current leads, said time-varying second
energy potential applied after a first predetermined time until a
second predetermined time when said time-varying second energy
potential is no longer applied, the first energy potential and the
second time-varying energy potential being designed to ensure
switching between first and second states having different
optical/energy properties in transmission or reflection.
2. The method as claimed in claim 1, wherein the constant first
energy potential is defined according to diffusion properties of
the active species in the multilayer.
3. The method as claimed in claim 1, wherein the time-varying
second energy potential is defined to force migration of the active
species into the multilayer.
4. The method as claimed in claim 1, wherein the first energy
potential and time-varying second energy potential are applied to
switch from the first state to the second state.
5. The method as claimed in claim 1, wherein the first energy
potential and time-varying second energy potential are applied to
switch from the second state to the first state.
6. The method as claimed in claim 1, wherein the first energy
potential and time-varying second energy potential are electrical
potentials.
7. The method as claimed in claim 6, wherein the time-varying
second energy potential is in pulsed, log(t), (1/t) or a+b form or
is in a form of a polynomial .function..times. ##EQU00004## in
which a.sub.i is positive or negative.
8. The method as claimed in claim 6, wherein the first energy
potential and time-varying second energy potential are compared
with a maximum first energy potential and a maximum time-varying
second energy potential, respectively, the maximum first energy
potential and maximum time-varying second energy potential being
determined as limiting values beyond which the functionality of the
system is no longer optimum.
9. The method as claimed in claim 1, wherein the first energy
potential and time-varying second energy potential are chosen from
voltage, current, or charge sources, taken individually or in
combination.
10. The method as claimed in claim 1, wherein the time-varying
second energy potential includes at least one constant pulse.
11. The method as claimed in claim 1, wherein the time-varying
second energy potential is such that the current or voltage
response is constant at any instant and equal to an initially
chosen value.
12. The method as claimed in claim 1, wherein the time-varying
second energy potential is such that the product of the potential
and the current is constant at any instant and equal to an
initially chosen value.
13. The method as claimed in claim 1, wherein the time-varying
second energy potential is such that the ratio of the potential to
the current is constant at any instant and equal to an initially
chosen value.
14. The method as claimed in claim 1, wherein the first energy
potential and time-varying second energy potential are positive or
zero.
15. The method as claimed in claim 1, wherein the first energy
potential and time-varying second energy potential are of opposite
sign.
16. The method as claimed in claim 1, wherein the first energy
potential and time-varying second energy potential are negative or
zero.
17. The method as claimed in claim 1, wherein the first energy
potential and time-varying second energy potential are of opposite
sign.
18. The method as claimed in claim 1, applied to an electrically
controllable system of electrochromic type, configured to switch
between two states of a colored state and a bleached state,
respectively.
19. The method as claimed in claim 1, wherein the first energy
potential and time-varying second energy potential are applied
between the current leads by a manual actuator.
20. The method as claimed in claim 1, wherein the first energy
potential and time-varying second energy potential are applied
between the current leads by an automatic actuator optionally
coupled to a detector.
21. An electrically controllable system having variable
optical/energy properties in transmission or in reflection,
including at least one carrier substrate with a multilayer that
allows migration of active species, or an electrochromic multilayer
including at least two active layers, which are separated by an
electrolyte, the multilayer being placed between two electrodes
connected respectively to upper and lower current leads
respectively comprising: first energy potential application unit
configured to apply a constant first energy potential; time-varying
second energy potential application unit configured to apply a
time-varying second energy potential between the current leads,
said time-varying second energy potential applied after a first
predetermined time until a second predetermined time when said
time-varying second energy potential is no longer applied; a
glazing unit configured to darken or lighten when the first energy
potential and the second time-varying energy potential switch
between first and second states having different optical/energy
properties in transmission or reflection, said glazing unit
includes a sunroof in a vehicle, or a side window or rear window in
a vehicle, or a rear-view window, or a windshield or a portion of a
windshield.
22. The system as claimed in claim 21, wherein said glazing unit
includes a display panel displaying graphical or alphanumeric
information, a window for a building, an aircraft cabin window or
windshield, a skylight, an interior or exterior glazing unit in a
building, a display cabinet, a store counter, which may be curved,
a protection glazing unit protecting painted objects, an anti-glare
computer screen, glass furniture, or a wall separating two rooms
inside a building or separating two compartments of a motor
vehicle.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application is the U.S. counterpart of WO 2005/103807,
and in turn claims priority to French Application No. 04/03800
filed on Apr. 9, 2004, the entire contents of each of which are
hereby incorporated herein by reference.
The present invention relates to a method of supplying an
electrically controllable device having variable optical and/or
energy properties. It relates more particularly to devices that use
electrochromic systems operating in transmission or in
reflection.
Electrochromic systems have been extensively studied. They are
known to comprise in general two layers of electrochromic materials
that are separated by an electrolyte and flanked by two electrodes.
Each of the electrochromic layers, under the effect of an
electrical supply, can inject charges reversibly, the change in
their oxidation state as a result of these injections/ejections
resulting in a change in their optical and/or thermal properties
(for example, in the case of tungsten oxide, a switch from a blue
color to a colorless appearance).
Switching the electrically controllable system consists of a
complex electrochemical process defined by a charge transfer
(electrical migration of the charged species (ions and electrons)
within a thin-film multilayer a few hundred nanometers in
thickness) and a mass transfer, associated with the displacement of
the charged species into the multilayer.
This switching is characterized by the contrast of the electrically
controllable system, by the uniformity of the coloration, by the
switching speed and by the preservation of these functional
properties after several coloration/bleaching cycles, namely the
durability.
The manufactures of electrically controllable systems have
developed techniques for improving all of these characteristics, so
as to obtain an optimized electrically controllable system.
Thus, better contrast is achieved by both improving and balancing
the charge capacity of the functional layers of the multilayer;
uniformity and switching speed are improved by optimizing the
conductivity of the conducting layers forming the electrodes that
connect the upper and lower active layers of the multilayer; using
a network of tungsten wires for feeding the current to the upper
electrode helps to improve uniformity. All these solutions result
in a durability corresponding to several tens of thousands of
cycles, which is generally representative of the lifetime of the
system.
Although these systems are entirely satisfactory, the manufacturers
have noticed that when these are integrated into large substrates
(with an active area of around 1 to 2 m.sup.2), the parameters such
as uniformity and coloring speed are no longer optimal and that, in
particular, the switching speed of the substrate is inversely
proportional to the size of the substrate.
The inventors have discovered, quite surprisingly, that it is
possible to model an electrically controllable system of this type
as an electrical system characterized by its individual resistors
and capacitors, and therefore generally its charge loss or its
impedance.
The presentation invention therefore aims to alleviate the
drawbacks of the prior techniques by proposing a method of
supplying an electrically controllable system that compensates for
these charge losses and therefore maintains, or even improves, the
abovementioned functional properties, even for large electrically
controllable systems.
For this purpose, the method of powering an electrically
controllable system having variable optical/energy properties in
transmission or in reflection, comprising at least one carrier
substrate provided with a multilayer that allows migration of
active species, especially an electrochromic multilayer comprising
at least two active layers, which are separated by an electrolyte,
the said multilayer being placed between two electrodes connected
respectively to current leads, namely the upper and lower current
leads respectively ("lower" corresponding to the current lead
closest to the carrier substrate, as opposed to the "upper" current
lead that is furthest from said substrate), is characterized in
that, in addition to a constant first energy potential P1, P1', a
time-varying second energy potential P2, P2' is applied between the
current leads, said first and second energy potentials being
designed to ensure switching between two states E1 and E2 having
different optical/energy properties in transmission or
reflection.
In preferred embodiments of the invention, one or more of the
following arrangements may optionally be furthermore employed: the
constant potentials P1 and P1' are defined according to the
diffusion properties of the active species in the multilayer; the
potentials P2 and P2' are defined so as to force the migration of
the active species into the multilayer; the energy potentials P1
and P2 are applied in order to switch from the state E1 to the
state E2; the energy potentials P'1 and P'2 are applied in order to
switch from the state E2 to the state E1; the energy potentials P1,
P1', P2, P2' are electrical potentials; the energy potentials P1,
P1', P2, P2' are chosen from voltage, current or charge sources,
taken individually or in combination; the second energy potential
P2, P2' consists of at least one constant pulse; the second
potential is of the pulsed, log(t), (1/t) or at+b form or is in the
form of a polynomial
.function..times. ##EQU00001## where a.sub.i is positive or
negative, or a linear or nonlinear combination of these forms; the
second potential is such that the current or voltage response is
constant at any instant and equal to an initially chosen value; the
second potential is such that the product of the potential and the
current is constant at any instant and equal to an initially chosen
value (this corresponds to a constant power regime); the second
potential is such that the ratio of the potential to the current is
constant at any instant and equal to an initially chosen value
(this corresponds to a constant impedance regime); P1 and P2 are
positive or zero; P1 and P2 are of opposite sign; P1' and P2' are
negative or zero; P1' and P2' are of opposite sign; the potentials
P1, P2, P'1, P'2 are compared with maximum potentials P1.sub.max,
P2.sub.max, P'1.sub.max, P2'.sub.max respectively, these potentials
being determined as limiting values away from which the
functionality of the system is no longer optimum; it is applied to
an electrically controllable system of the electrochromic type,
switching taking place between the colored state E1 and the
bleached state E2; the energy potentials are applied between the
current leads by a manual actuator; and the energy potentials are
applied between the current leads by an automatic actuator
optionally coupled to a detector.
The invention will be described in greater detail with regard to
the appended drawings in which:
FIG. 1 is a front view of the face 2 of a glazing unit that
incorporates an electrically controllable system, especially one of
the electrochromic type, which can be supplied using the method
according to the invention;
FIG. 2 is a sectional view on AA of FIG. 1;
FIG. 3 is a sectional view on BB of FIG. 1;
FIG. 4 illustrates the variation in light transmission as a
function of time for various potential values P'2; and
FIG. 5 illustrates the rate at which the change of state occurs for
different potential values P'2.
In a preferred embodiment of an electrically controllable system,
for example of the electrochromic type, allowing the supply method
according to the invention to be implemented, it comprises an
all-solid-state electrochromic thin-film multilayer made up of an
active multilayer 3 placed between two current collectors 2 and 4.
The collector 2 is intended to be in contact with the face 2. A
first array of conducting wires 5 (visible in FIG. 1) or an
equivalent device is used to supply the collector 4 with electric
current; a second array of conducting wires 6 (also visible in FIG.
1) or an equivalent device allows the lower collector 2 to be
supplied with electric current.
The collectors 2 and 4 and the active multilayer 3 may have either
substantially identical sizes and shapes, or substantially
different sizes and shapes, and it will then be understood that the
path of the collectors 2 and 4 will be adapted according to the
configuration. Moreover, the sizes of the substrates, in particular
S1 may be essentially greater than those of 2, 4 and 3.
The collectors 2 and 4 are of the metal type or of the TCO
(Transparent Conductive Oxide) type made of ITO, F:SnO.sub.2 or
Al:ZnO, or they may be a multilayer of the TCO/metal/TCO type.
Depending on the configurations, they may be omitted and, in this
case, the current leads 5 and 6 are directly in contact with the
active multilayer 3.
A preferred embodiment of the collector 2 is formed by depositing,
on the face 2, a 50 nm SiOC first layer surmounted by a 400 nm
F:SnO.sub.2 second layer (the two layers preferably being
deposited, in succession, by CVD on the float glass before
cutting).
A second embodiment of the collector 2 is formed by depositing, on
face 2, a bilayer consisting of an SiO.sub.2-based first layer
which may or may not be doped (especially doped with aluminum or
boron) about 20 nm in thickness surmounted by the an ITO second
layer of about 100 to 600 nm in thickness (the two layers being
preferably deposited, in succession, under vacuum, by reactive
magnetron sputtering in the presence of oxygen, possibly carried
out hot).
Another embodiment of the collector 2 is formed by depositing, on
face 2, a monolayer made of ITO about 100 to 600 nm in thickness (a
layer preferably deposited, under vacuum, by reactive magnetron
sputtering in the presence of oxygen, possibly carried out
hot).
The collector 4 is an ITO layer with a thickness of 100 to 500 nm,
also deposited, on the active multilayer, by reactive magnetron
sputtering.
In FIG. 1, the current leads 5 are metal wires connected to metal
shims. The metal wires are for example made of tungsten (or copper
or molybdenum), said wires being optionally coated with carbon,
partially oxidized, with a diameter of between 10 and 100 .mu.m and
preferably between 20 and 50 .mu.m, these being straight or
corrugated, and deposited for example on a PU sheet using a
technique known in the field of wire-based heated windshields, for
example that described in patents EP-785 700, EP-553 025, EP-506
521, EP-496 669.
One of these known techniques consists in using a heated press roll
that presses the wire against the surface of polymer sheet, this
press roll being supplied with wire from a feed spool via a
wire-guide device.
As is known, the metal shims are copper strips optionally coated
with a tin alloy, with a total thickness of typically 50 .mu.m and
with a width of between 3 and 8 mm.
The current leads according to another embodiment are obtained by a
screen-printing technique, the leads being directly deposited on
the enameled regions of the face 2. This screen printing,
especially based on silver, may also be deposited on the ITO layer.
A conductive paste may also act as a current lead and, in this
case, it is in contact with the ITO layer or with the enamel layer
present on face 2.
The active multilayer 3 shown in FIGS. 2 and 3 is made up as
follows: a 40 to 100 nm layer of anodic electrochromic material
made of hydrated iridium oxide (it may be replaced with a 40 to 300
nm layer of hydrated nickel oxide), which layer may or may not be
alloyed with other metals; a 100 nm layer of tungsten oxide; a 100
nm layer of hydrated tantalum oxide or hydrated silica oxide or
hydrated zirconium oxide; a 370 nm layer of cathodic electrochromic
material based on hydrated tungsten oxide.
Moreover, the glazing unit shown in FIGS. 1, 2 and 3 incorporates
(but not shown in the figures) a first peripheral seal in contact
with the faces 2 and 3, this first seal being suitable for forming
a barrier to external chemical attack.
A second peripheral seal is in contact with the edge of S1, the
edge of S2 and the face 4, so as to produce: a barrier; a means of
fitting the unit into the vehicle; a seal between the inside and
the outside; an esthetic function; a means of incorporating
reinforcing elements.
The substrates used to form the glazing unit, incorporating the
electrically controllable system formed in particular by the
multilayer 3, are of the type comprising substrates made of glass
or of organic material (PMMA, PC, etc.). As examples, it is
possible to use, as glass substrates, flat glass sold by
Saint-Gobain under the brand name PLANILUX, with a thickness of
about 2 mm for motor vehicle applications, and a thickness of
substantially 5 mm for building applications.
It is also possible to use curved and/or toughened glass,
optionally bulk-tinted (blue, green, bronze or brown).
Of course, these substrates may have a very wide variety of
geometrical shapes: they may be squares or rectangles, or more
generally still of polygonal shape, or of curved profile defined by
rounded or wavy contours.
The current leads are connected, via wire connections or the like,
to a power supply, the mode of operation of which is as follows: an
energy potential P is applied between the current leads, this
potential being suitable for causing the active species to migrate
into the electrically controllable system and for generating a
change of state characterized by a change in the optical/energy
properties, in transmission or in reflection, of the system.
In the nonlimiting example given (this is an electrochromic
system), the active species consist of the electrons coming from
the electrodes or counterelectrode and the cations from the
electrolyte, the change of state for this type of system being
expressed in terms of the color modification, or precisely a
reversible switch between a colored state E1 and a bleached state
E2.
It will be recalled that, for a change of color state to occur, it
is necessary to have alongside the layer of electrochromic material
a source of cations and a source of electrons, formed respectively
by a layer of an ionically conductive electrolyte and by an
electronically conductive layer. In addition, the system includes a
counterelectrode, which is itself capable of reversibly injecting
and ejecting cations, symmetrically with respect to the layer of
electro-chromic material. With a cathodic electrochromic material,
such as for example tungsten oxide, it is preferred to use a
counterelectrode made of an anodic electrochromic material such as,
for example, iridium oxide which is colorless in the reduced state
and yellow-gray in the colored state. The cation source is formed
by the electrolytic layer of the system, for example based on
tantalum or tungsten, and the electron source is formed by the
electronically conductive second layer, the two electronically
conductive layers forming the two electrodes between which the
energy potential difference is applied.
The energy potential P consists in fact of a time-varying
electrical potential difference which comprises: a constant
component P1 or P'1, whose amplitude is constant over time,
depending on the state, colored or bleached, this constant
component being combined with a variable component P2 or P'2, whose
amplitude varies over time, depending on the colored/bleached state
and vice versa.
As a variant, the energy potentials P.sub.i and P'.sub.i may
consist of current, voltage or charge sources, i=1 and/or i=2.
Thus, for example in the case of the electrochromic system
described above, a positive voltage P1, of between 0.5 V and 2 V,
preferably between 1 and 1.5 V and even more preferably
substantially close to 1.2 V, for switching between the colored
state and the bleached state and a negative voltage P'1, of between
-0.5 V and -3 V, preferably between -1 and -2 V and even more
preferably approximately -1.6 V for switching between the bleached
state and the colored state are applied for a few seconds between
the current leads.
In addition, overvoltages P2 and P'2 are associated with these
voltage levels P1 and P'1, respectively: P2 is a positive voltage,
whose amplitude varies over time, which may be of the pulsed,
log(t), (1/t) or at+b form, or may be in the form of a pulsed
polynomial
.function..times. ##EQU00002## where a.sub.i is positive or
negative, or a linear or nonlinear combination of these forms; and
P'2 is negative, whose amplitude varies over time, and may take the
same form as P2.
Within the context of the invention, the term "pulsed" refers to a
voltage P2 that can take the form of a mathematical function, or
example of the Heaviside type and expressed in the following
form:
.function..times..function..function..times..times..times..times..times.
##EQU00003##
As a variant, at least one of the potentials P1, P'1, P'2 may also
be of the pulsed form and may be expressed in a similar way to
P2.
As illustrated in FIG. 4, several overvoltage levels for P'2 are
chosen, to be applied for the same time (1 s), namely -1.4 V; -2.4
V; -3.4 V, respectively. With a -1.4 V level, the light
transmission level of around 10% (corresponding to a transition
between the bleached state and the colored state) is reached twice
as quickly (4 seconds) than in a situation with no overvoltage,
i.e. P'2=0 (8 seconds).
It should also be noted that the increase in voltage level is not
significant; if the level is too high, this may lead to destruction
of the electrically controllable multilayer (appreciable reduction
in or even loss of the functional properties).
This is because the overvoltage level P'2 applied is tailored
according, on the one hand, to the optimum switching speed of the
electrochromic system and, on the other hand, to a limit level or
threshold beyond which the multilayer risks being degraded over
time (i.e. the durability of the electrically controllable system
is optimized).
To prevent this malfunction, before applying the voltage level P'2,
this is compared with a level P'2.sub.max that represents a
threshold voltage beyond which the electrically controllable system
risks being damaged.
In FIG. 5 the aim is to obtain a light transmission that is
substantially similar to the previous case (the same level of
T.sub.L obtained after a similar time, i.e. about 4 s). It may be
noticed that by applying a -0.7 V pulse for 3 s to P'2, 10% T.sub.L
level is obtained, as shown in the table below.
TABLE-US-00001 T.sub.L level Time to reach x % coloration (s) (%)
Control -0.7 V/3 s Ratio 50 1.1 (.+-.0.1) 0.7 (.+-.0.1) 1.6 30 2.1
(.+-.0.2) 1.2 (.+-.0.2) 1.8 10 5.0 (.+-.0.2) 2.0 (.+-.0.2) 2.5
In a similar way to P'1 and P'2, a positive overvoltage P2 (which
is also less than the maximum overvoltage P1.sub.max) is applied as
a complement P1 in order to increase the rate of transition between
the colored state and the bleached state).
Thus, with a similar electrically controllable system, by applying
a constant voltage P1=1.6 V and then a pulsed overvoltage of P2=0.4
V for 1 second, a similar effect is obtained, namely an increase in
the rate of switching during the transition from the colored state
to the bleached state (in practice, a gain of around 1.5 to 2 s is
achieved for switching from a 40% T.sub.L to a 7% T.sub.L).
Of course, the potential difference values given above have been
optimized for a nonlimiting example of a multilayer structure, and
it will be readily understood that, for another multilayer
structure (different dimensions, different electrochromic material,
etc.), these values will be different. However, irrespective of the
nature of the electrically controllable structure (for example an
all-polymer system), the method of supplying it remains valid and
it will simply be necessary to adapt the amplitudes and the
durations of application of the applied potentials P1, P'1, P2, P'2
(the P.sub.i and P'.sub.i may be positive, negative, zero, of
opposite sign and i=1 or 2, taken individually or in
combination).
The glazing unit incorporating the electrically controllable system
may be applicable either in the automobile field or in the building
field. For example, in the automobile field, it may be a sunroof
for a vehicle, able to be activated autonomously, or a side or rear
window for a vehicle, or a rear-view mirror, or a windshield or a
portion of a windshield. In the building field, it may for example
be a display panel for displaying graphical and/or alphanumeric
information, a window for buildings, an aircraft cabin window or
windshield, a skylight, an interior or exterior glazing unit for
buildings, a display cabinet, a store counter, which may be curved,
a glazing unit for protecting objects of the painting type, an
anti-glare computer screen, glass furniture, or a wall separating
two rooms inside a building.
The electrically controllable system is activated by a manual
actuator, for example a switch positioned in the room or in the
automobile (especially on the dashboard), or by means of an
actuator or automated detector, optionally controlled and/or
time-delayed, taking into account the environmental conditions of
the glazing (brightness, glare sensor) in order to be determined.
The detector may be controlled by the interior or exterior
brightness via a suitable probe. In the case of an interior probe,
this may be an ambient light probe or a sensor placed for example
on the surface of a desk or on the dashboard. The control signal
may also derive from the ratio of a brightness measurement taken
inside (for example against the glazing, to a reference
measurement). In the latter case, the control circuit includes a
signal processing phase. The detector may also be time-controlled
or controlled by the value of the electrical potential reached, by
the value of the current or by the amount of charge that has
flowed.
The invention described above offers many advantages as in
particular it allows the switching rate of electrically
controllable systems, especially those of the electrochromic type,
to be increased while maintaining their durability.
* * * * *